Lavianga's Spirits Mana Flask effect drops off

Sometimes during gameplay the effect of Lavianga's Spirits Mana Flask doesn't work until I manually reequip it on character.

The mana regen doesn't work as well as mana cost reduction from tree.

Character: Druid Werewolf

From what I noticed it appears when:
- Character respawn
- Map enter

Probably the issue is with character spawn but it's not consistent tho.